1. Field of the Invention
The present invention relates to a gateway apparatus for interfacing between an exchange and an IP network.
2. Description of Related Art
Conventionally, various technologies have been proposed for monitoring whether a failure occurs in a gateway apparatus that connects an IP (Internet Protocol) network with a PSTN network (Public Switched Telephone Network).
For example, in prior art gateway apparatus disclosed by patent reference 1, a VoIP (Voice over Internet Protocol) gateway apparatus on a transmit side monitors whether a failure occurs in an IP network, generates a status report signal including monitoring results, and periodically transmits it to another VoIP gateway apparatus, which is the party at the other end of communications, via a voice communication path. Then, when the VoIP gateway apparatus does not receive a status report signal from the party at the other end of communications within a predetermined time period, the VoIP gateway apparatus determines that a failure has occurred in the voice communication path and performs a disconnection process of disconnecting a corresponding call.
A prior art voice gateway apparatus disclosed by patent reference 2 periodically checks failure information about each of two or more voice gateway apparatus which can be the party at the other end of communications, and stores it in a status management table. The prior art voice gateway apparatus then refers to the status management table when transmitting data to the party at the other end of communications, and controls so as not to select any voice gateway apparatus in which a failure has occurred as the party at the other end of communications, thereby shortening the length of time that the call is connected.    [Patent reference 1] Japanese patent application publication (TOKKAI) No. 2002-290460    [Patent reference 2] Japanese patent application publication (TOKKAI) No. 2002-290550
A problem with prior art gateway apparatus is that when a failure occurs in a piece of hardware corresponding to a trunk channel of the gateway apparatus, no components of the gateway apparatus notify the occurrence of the failure to another gateway apparatus which is the party at the other end of communications, and therefore call blockage occurs in the trunk channel in which the failure has occurred.
Another problem with the prior art gateway apparatus is that no components notify the occurrence of a failure that has occurred on a PSTN side to a station which is disposed opposite to the prior art gateway apparatus.